Oklahoma Electrical Practice Exam

What is the largest ampacity allowed for an aluminum AWG type TW #10 wire?

1. 20 amp Breaker

2. 25 amp Breaker

3. 30 amp Breaker

4. 35 amp Breaker

The correct answer is: 25 amp Breaker

The largest ampacity allowed for an aluminum AWG type TW #10 wire is 25 amps. This is primarily determined by the National Electrical Code (NEC) that establishes guidelines for safe electrical wiring practices. The ampacity of wires can vary based on material (which influences the amount of current a wire can safely carry), insulation type, and the conditions under which the wire is installed. For aluminum conductors, the ampacity rating will generally be less than that of copper conductors due to aluminum's lower conductivity. The standard tables found in NEC give specific ampacity ratings based on wire gauge and type, taking into account factors such as temperature ratings and the environment in which the wire is installed. Thus, a #10 AWG aluminum wire typically has a maximum ampacity of 30 amps, but it is prudent to follow the NEC's recommendations and local codes, which often suggest using a 25 amp breaker for circuits utilizing this type of wire, particularly to avoid overloading and potential hazards. This ensures the wire operates within safe parameters, preventing overheating and reducing the risk of electrical fires.